Heat exchange assembly



May 20 1947- G. R NEUMANNZETAL 2,420,757

HEAT EXCHANGE ASSEMBLY Filed Nov. 5, 1943 3 Sheets-Sheet 1 May 20, 1947- s. R. NEUMANN ETAL 2,420,757

3 Sheets-She Filed Nov. 5,1943

Patented May 20, 1947 HEAT EXCHANGE ASSEMBLY George R. Neumann, St. Clair Shores, Eugene F. Farrell, Grosse Point Woods, and Charles S. Davis, Jr.,,Detroit, Mich., assignors to Borg- Warner Gorporation, Chicago 4, UL, a corporation of Illinois Application November 5, 1943, Serial No. 509,078

scams. (oi. 257-241) This invention relates to a heating unit. It

claims the details of the construction .of the heater unit shown in applicants copending appli-' cation, Serial No. 509,076, executed and filed 6011-, currently herewith; i

More particularly, this invention is directed to an improved form of heat exchanger. It is an object of this inventionto provide an improved device which is particularly adapted to the burnin of atomized fuel.

It is a further object of the invention to provide a method of fabricating a heat exchanger of the type forming the subject matter of this invention.

It is an object of the invention to provide a,(

light weight, simplified form of heat exchanger, one which may readily be assembled from a plurality of substantially identical units, and one in which said'identical units may be cheaplymanufactured, as stampings or the like.

It is a further object to provide a heat exchanger assembly and method of fabricating the same primarily from sheet metal, preferably stainless steel, including the use of identical sections arranged to be joined together by brazing or spot welding in a manner such that there is no danger of the combustion gases mixing with the lower pressure air being passed through the extaken onthe lines 3-! of Fig. llooking in the directionof the arrows;

Fig. 4 is a fragmentary, longitudinal, elevational 1 view taken on the lines 4-4 of Fig. 1, looking in the direction of the arrows;

Fig. 5 is a fragmentary perspective view, showing one form of what may be referred to as a channel element or section used to conduct air through the heat exchanger and likewise forming a part of the exhaust conduit or manifold, a portion of another channel member being shown as abutting and attached to the main channel member, whereby there is illustrated the method of joining two channel members together in side by side relationship to form said exhaust conduit and a portion of the air conducting channel for changer, into the room or other object to be 1 heated.

It is an object of the invention to provide a construction whereinthe burned gases ordinarily leave the heat exchanger in a circuitous route and thereby transfer a substantially greater portion of heat to the heat exchanger walls which come into wiping contact with air to be heated.

It is a further object to disclose an improved form of device which is easily manufactured by in the appended claims, reference being made to,

the accompanying drawings that form a partof this specification wherein: a

Fig. 1 is a longitudinal, sectional, 'elevational view of the device forming the subject matter of this invention; v v

Fig. 2 is a cross-sectional view taken on the line 22 of Fig. 1 looking in the direction of the arrows;

Fig. 3 is a fragmentary cross-sectional *view the heat exchanger; and

Fig. 6 is a fragmentary cross-sectional view showing a modified form of device for the air and exhaust conduit.

The drawings are to be understood as being more or less of a schematiccharacter for the purpose of disclosing a typical or preferred form of the improvements contemplated herein, and in these drawings like reference characters identify the same parts in the several views.

Referring first to the construction shown in Figs, l through 5, there is illustrated-as will be seenparticularly from Figs. 1 and 2-a heat,

exchanger comprising a plurality of substantially identical trough-like channel elements. herein broadly referred to as channel elements 20, arranged in a group forming a cylindrical unit, and having additional portions hereinafter more fully described, completing the heat exchanger assembly.

As will he more clearly discerned from Fig. 5, the channel element 20 used in building upthe heat exchanger assembly is preferably made by stamping out or otherwise forming a sheet of metal, preferably stainless steel, into the shape shown in Fig. 5. Briefly, this shape consists of bending the sheet of metal into what may be roughly described as a trough-like shape of generally U-shaped cross-section, in which the edges of the material are flat and form an attaching land or plane for the purpose which will hereafter more clearly appear. These lands or planes around the edges of the material consist of top edges 28, vertical end edges 28, and bottom'edges 30, and end edges 32 at the end of the edges 28. The sides of the trough 20 flare outwardly at an angle with respect to the bottom 3|, and the channel element 20.

mined by the radius from the center of the heat exchanger unit to the bottom of the trough assemblies as will be apparent from Fig. 2.

' attached together are preferably brazed or welded or otherwise rendered gas-tight and solidly assembled along the lands 28, 28 and 32. The side channel 38 is provided on each side at one end with the conca'ved or depressed portion 30, and at the other end with a cut-out or. recess 40.

Examination of Figs. 1, 3 and4 clearly illustrates the method of assembling the exhaust ring 42 to the, channel member 20. This exhaust ring 42 is seated in the recess 40, and is perforated so that the edges of the perforations conform to the edges of the recess 40 whereby the exhaust ring is provided with ports l4, opening into the side channels 36. The edges of the recess 40 are welded, brazed, or otherwise attached to the exhaust ring 42 ina gas-tight fit (as shown at N d in Fig. 4)

The bottom land 30 on one end of the device (shown in Fig. 1 as the left-hand end), is secured to a cover plate I of stainless steel or the like, by any convenient method such as brazing. This cover plate 48 may be provided .with a port 49 and a removable cap 50, which cap 50 may be taken off for the purpose'of directing the exhaust gases out of the end of the firing chamber 22 formed by the assembly of the channel elements into a circular-barrel-like shape. It is understood'that the cap 50 will normally remain port 49, and be retained in in position over the place by the bayonet joint in the ordinary way.

The cover plate 48 does not extend past the bottom land 30 of the assembly, and the cover plate 45 may be provided with a bead or circumferential upstruck fiange portion 54, to facilitate welding the edges to the land 30.

At its other end, the channel member 20 has a similar land 30 along its bottom. As will be noted flanged edges fits over from Fig. 1 'acollar 58 in the form of a stainless steel ring is inserted and welded or otherwise attached to the land 30. This collar 58 carries the assembly (preferably prefabricated) consisting of a bowl-shaped end member 58 into which is fastened an end cap 60 having a gas Jet 62 with means such as a threaded opening for attaching a gas line H from a carburetor or other source of fuel. The gas jet 62 extends into the firing chamber and is provided with holes or openings whereby carbureted fuel is discharged into the firing chamber 22. The cap 60 is likewise provided with a spark plug 68 by means of which a spark for igniting the fuel may be introduced into the firing chamber.

The end member 58 is preferably provided with a plurality of holes 68 around the portion ad- Jacent to the collar 56. An end cap 10 having a flange portion and a center opening with the cap 60 and end member 58 and is brazed,'welded or otherwise attached to the collar 56 and end member 58 as is apparent from Fig. i. This end plate I forms, with the chamber where they will and any unburned gas to be burned in the firing end member 58, a channel 12 from which the openings 68 lead to the firing chamber. An engine exhaust connection may be provided for the end plate whereby the exhaust gases from an auxiliary engine may be returned to the firing contribute their heat chamber.

It is understood that the assembly comprising the collar 56, the end member 58, the cap 60, gas jet 82, and end plate 10 will be formed in production before the assembly and attachin of the collar to the lands 30.

It is thus seen that a closure comprising a firing chamber 22 is formed by the channel members and end plates and end plate assembly above described.

In order to provide a surrounding cover, there is placed over the assembly above described, a

pressure does not firing chamber, but, effectively wipes the surfaces shell 14, either in sections or as a complete unit which is seated over the outer circumference of the assembled channel members (see Fig. 2). Preferably this shell 14 is provided with V -shaped indentations or concave portions 15 corresponding with the center of each channel member 20 when assembled, whereby air forced through the channel 20 under the shell 14 will be accelerated due to the restricted construction. Preferably the ends of the shell 14 as shown at 1B are left fiared so that air pressure against the end of the device will be forced through said channels. This air mingle with the gas from the of the channel member, whereby the air is heated and may be discharged into the room or other place to be heated. It will be understood that considerable air current may be developed by a fan blowing on the end of said exchanger as is indicated by Fig. 1, and will thus overcome any inertia. This heat exchanger when used in assembly with a fan arrangement, may be used for such purposes as preheating airplane engines in very cold climates, heating rooms and the like.

It is understood that the exhaust from the firing chamber is conducted through the concave portion 38. as indicated in Fig. 1 into the side channels 36, where much of the heat of the exhaust is delivered to the metallic surfaces in a wiping action, the exhaust then passing through the opening recess from where it is discharged at the exhaust outlet 18.

Referring to the modified construction shown in Fig. 6, the channel element is formed with overlying top surfaces 82 and 84, and with concave side indentations 85. The channel elements otherwise are similar to those of Fig. 5, and in assembly they are attached together by brazing, soldering, or other leak-proof manner, at their top edge portions 88. In this manner the need for a separate cover is eliminated. It is understood that the end lands for the side channels which'correspond shape for shape with the side channels 38, are brazed together.

It does not matter if the various channel elements are tightly fastened along their bottom edges, in that exhaust gas from the firing chamber 22 escaping through spaces between the channel elements at the bottom will merely enter the side channels 80 or 36 as the case may be, and be conducted into the exhaust ring in the regular way. It is noted, however, that by providing the concavity 38, the gases take a circuitous route which gives maximum heat dis- 40 into the exhaust ring 42 is charging result before'the gases find their way out of the exhaust I8.

In operation, the device is readily assembled and the edges quickly fastened together by brazing or welding in the manner indicated. It is noted that all of these edges to be fastened are so positioned as to be readily accessible for that ,purpose.

Unburned gases are introduced into the firing chamber 22 through the jets 60, where they are ignited by sparks from the spark plugs 66, and are burned in the firing chamber. The exhaust gases from the engine are introduced through the port 68 and mingle with the burning gases in the firing chambers whereby they are completely combusted, if not already fully 50, and then the burned gases from the firing chamber and engine exhaust pass through the port created by the indented side portions of two connected channel members forming a passage for exhaust gases from said heat exchanger. i

3. A heat exchanger having a plurality of channel members, each said channel member being of substantially uniform construction and formed of a sheet metal stamping, each said channel member having a trough-like construction wherein the sides are indented inwardly and the edges are folded over the top and closed together, depressions on each side of each channel member from the bottom thereof to the indented portion,

the concavity 38 into the side channel 36, travel nection with one specific embodiment thereof, it is to be understood that this is by way of illus-' tration and not by way of limitation and the scope of our invention is defined solely by the appended claims which should be construed as broadly as the prior art will permit.

We claim:

1. As an article of manufacture a heat exchanger in which there are a plurality of troughshaped channel members of substantially uniform construction, each said channel member comprising a stamping of fire resisting material, and being substantially trough-shaped with one end of each said'channel member on said side thereof having a cutaway portion connected to said indented portion, said channel members being connected together at their top marginal edges thus forming a plurality of conduits each separate from the other.

4. A heat exchanger assembly comprising a plurality of side-by-side identical members ar- 1 ranged in annular array providing a hollow body;

each said member comprising an elongate stamp- I ing having an approximately smooth bottom wall,

and side walls diverging outwardly from the iongitudinal edges thereof; fiat marginal lands along the outer longitudinal and the transverse end margins of said side walls; depressed regions extending longitudinally of said side walls, said regions being encompassed by said lands and being extended inwardly toward each other; recesses in the ends of said side walls at one end of said member; and inward bulges in the depressed regions of said side walls adjacent the flattened edge portions, the side portions of each channel member being indented, a depressed portion from the bottom marginal edge of each channel member leading to the indented side,

portion on each side thereof, and an escape recess at the other end of said channel member from the depressed portion, on each side thereof, said channel members being attached together on their side and end marginal portions thereby forming a plurality of separate conduits, one of said conduits being for air and the other said conduit forming an escape path for heated prodnets of combustion.

2. In a heat exchanger, a plurality of channel members comprising sheet metal stampings with indented side portions and a depressed portion from the bottom marginal edge on each side of each channel member connecting with the in.- dented side portions, each said depressed portion being near one end of said channel member, and a cutaway portion near the other end of each channel member opening to said indented side portion, said channel members being connected together in sealed relationship at each side near the top edge portion thereof, the interior of each channel member forming a channel for air and other end of said member; the said members being assembled with the lands of each member opposing and anchored to the lands of proximate members; means defining closures for the ends of the central portions of the assembly which are bounded by the bottom walls of said members; and a cylindrical shell encompassing said members and anchored to the outer edges of the side walls of said members, the construction and arrangement of said members being such as to provide a plurality of alternate conduits respectively for air and heated products of combustion.

5. A heat exchanger assembly as defined in claim 4 wherein the cylindrical shell has longitudinal depressions entering the spaces between the side walls of the respective members.

GEORGE R. NEUMANN. EUGENE F. FARRELL. CHAS. s. DAVIS, JR.

REFERENCES crrnn The following references are of record in. the file of this, patent:

UNITED STATES PATENTS Germany Jan. 16, 1940 

